Process for treating cellulose ethers to improve their dissolving properties



Patented Aug. 24, 1948 PROCESS FOR TREATING CELLULOSE ETHERS TO IMPROVETHEIR DIS- SOLVING PROPERTIES Leon Lilienfeld, deceased, late of Vienna,Germany, by Antonie Lilienfeld, administratrix, Winchester, Mass,assignor to Lilienfeld Patents, Inc., Boston, Mass., a corporation ofMassachusetts No Drawing. Original application July 6, 1938,

Serial No. 217,776. Divided and this application July 12, 1944, SerialNo. 544,636. In Great Britain July 12, 1937 4 Claims.

The prior researches of this inventor have shown that alkali-solublecellulose ethers exist which do not dissolve in aqueous caustic alkalisolutions at room temperature, with the production of solutions whichare sufficiently concentrated to serve for the direct production ofartificial structures. Such ethers, in some instances do not dissolve atall therein, at room temperature. Some of such ethers do not dissolveexcept very incompletely, therein at room temperature, In certain caseseven, this is equally true at some temperatures below room temperature,e. g. at some temperatures near C. or somewhat above but below roomtemperatures they do not dissolve, but they do dissolve therein at verylow temperatures, e. g. at minus 10 or at the freezing point of thesolution. But such alkali-solubl cellulose ethers, of the statedproperties are still highly useful for the manufacture of shapedstructures having particularly useful properties.

The only way of bringing such ethers into substantially completesolution in aqueous solutions of caustic alkali, at room temperature,heretofore known, is the process described in British specification No.212,864 to Lilienfeld which is based on the discovery that it ispossible to obtain a solution of the whole substance of the celluloseethers of the aforementioned types, in caustic alkali solution, at roomtemperature by contacting them with caustic alkali solution and coolingthe thus obtained suspensions or incomplete solutions to a temperaturebetween plus 5 C. and minus 25 C. until dissolved, and thereafterallowing the temperature to rise to room temperature or to a temperaturebetween room temperature and 0 C.

In most cases, recourse must be taken to temperatures at which thesuspensions or incomplete solutions freeze or form ice crystals, i. e.to temperatures which are considerably below 0 C., for example minus tominus C. and in certain cases even minus C.

This shortcoming of the cellulose ethers of the aforementioned types isparticularly serious with such users of alkali-soluble cellulose ethersas do not manufacture them themselves but purchase them from chemicalconcerns and who desire to produce shaped structures of supreme quality.Owing to the inability of such alkali-soluble cellulose ethers todissolve in caustic alkali solution at room temperature or at atemperature not substantially lower than room temperature, such usershave no other option but to go to the expense of fitting up and runninga refrigeration plant or to content themselves with producing 2 thearticles in question from the hitherto known alkali-soluble celluloseethers which will dissolve in caustic alkali solution at roomtemperature and which ethers are incapable of yielding shaped structureshaving so excellent properties as the shaped structures made from suchcellulose ethers as can be dissolved only with the aid of freezing theirsuspensions or incomplete solutions in caustic alkali solution.

In addition, in many cases, the filtering capacity of the solutions ofthe cellulose ethers of the aforementioned types is rather poor; so muchso, that frequently filtration through cotton wool is only possible withthe aid of a pressure of 8 to 10 atmospheres or even more, and even thenthe filtration proceeds very slowly and also this only, when the cottonwool is changed from time to time.

The only process known hitherto for converting the alkali-solublecellulose ethers of the aforementioned types into cellulose ethers whichwill dissolve at room temperature or at a temperature between 0 C. androom temperature consists in subjecting the cellulose ethers to theaction of heat, preferably by treating them at a temperature not lowerthan C. for a certain time, attended by a considerable reduction of theviscosity and thus by a degradation of the properties of shapedstructures made from the initial cellulose ethers. Such a process isclaimed in the copending application Ser. No. 159,606 of August 1'7,1937 filed by Leon Lilienfeld (now Patent 2,265,919).

Moreover in cases in which the cellulose ethers are prepared by means ofmoderate proportions of etherifying agents (for example by means of 10to 11 per cent, of ethylene chlorohydrin) the heating must be conductedat a temperature substantially exceeding 100 C. to yield a celluloseether which will dissolve in caustic alkali solution at roomtemperature. Such temperature, however, decreases the viscosity of thecellulose ethers to a high degree and leads to final products yieldingshaped structures having properties considerably inferior to theproperties of the shaped structures obtainable from the' celluloseethers before heating.

Consequently, althoughvery useful in all cases in which an improvementof the dissolving capacity of the cellulose ethers attended by areduction of their viscosity is desired, the process in question isperfectly incapable of converting cellulose ethers which do not dissolveor do not completely dissolve in caustic alkali'solution at roomtemperature with the formation of solutions having a concentrationsufficient to be adapted for the production .of shaped structures, into:cellulose ethers which will dissolve therein at room temperature andwhich, nevertheless, excel by a high degree of viscosity and yieldartificial structures when they are dissolved at a temperature subhavingproperties in no respect:inierior torthe properties of shaped structuresproduced-from"; cellulose ethers which do not dissolve or only lire.

completely dissolve in caustic .alkali solution at room temperature andwhich ,can;,-be dissolved, therein only by the refrigeration or-freezingmethod.

Finally, even when conducted at temperatures considerably exceeding 1000., the aforementioned heat treating process is incapable of pro ducingcellulose ethers whichwi'll'dissolve in;

caustic alkali solution at room temperature or at a temperature notsubstantially lower than room stantially lower than room temperature,

' Areprecipitatedi by means of a precipitant se- 1looted-imm tablegroupconsisting of water, alkali res recognition that ji'ts -,most importantand advan- -tageous,;-embodiment consists in using water as temperaturefrom such cellulose etl1ersxas-- are.

prepared with very small proportions of. etherif-yingagents, for examplewith such proportions of etherifying agents as are set forth under item10: of that part of the present specification which deals-with thetechnical advance marked bythe' present process;

For the reasons explained: above, the lack of cellulose ethers whichwill directly dissolve in caustic alkali solution at room temperature.orat a temperature not substantially lower than room temperature, whichhave a, viscosity warranting their capability of producing" high-gradeshaped structures and which can beworked up" into shapedstructures; inno respect inferior to the shaped structures obtainable from suchcellulose ethers as canz'be dissolved or completely dissolved incausticalkali solution by the freezing method only; is a long-felt wantin'the technology and the industrial utilization of alkali-solublecellulose: ethers.

The. present. invention supplies this desi'deratuin in thechemistry andapplied chemistry of alkali-soluble cellulose jethers in as muchas itleads. to cellulose. ethers whichawill'. dissolve in caustic alkalisolution at room temperature or at a temperature not" substantiallylower than room" temperature a-ndwhose solutions "neverthelessyiel'd'structures, such as artificialthreads or filmor the like, havingproperties of shaped structures produced from such cellulose ethers ascan be dissolvedonly by the freezing operation.

The present invention resides-inthe discovery that 'cellul'ose etherswhich will dissolve in caustic alkali solution at room temperature or'at le'a st at a temperature not substantially lower thanroom-temperature and which excel by properties hitherto unobserved inany cellulose ether which will-directlydissolve in caustic alkalisolution at room temperature or at a temperature not substantially lowerthan room temperature are obtained:

When solutions of cellulose ethers which will not dissolve or will onlyincompletely dissolve in causticalkali solution at room temperature orat a temperature not substantially lower thanroorn temperature and whichyield"solutions-'sufliciently concentrated to be suitable for thepreparation of shaped structures and other useful articles only whenthey are dissolved by' cooling" their suspensions or incomplete"solutions in'caustic alkali solution to a temperature at whi'chfreezingor formation of crystals occurs, or

When solutions of cellulose ethers which will not dissolve or willonlyincompletely dissolve in: caustic alkali solution atfroom temperature orata: temperature not substantiallyflower than: room.

' carhonatesx and carbon dioxide or carbonic acid respectively,

The, present invention further resides in the precipitantfor.the-fiolutions of the cellulose ethers serving as initial materialsin the present in- .v nti n;-;

Gonsequentlmthe object of the present inventiorr is thepreparation ofcellulose ethers which can be dissolved without freezing and inmost.:.cases at room temperature or at a temperature not substantiallylower than room temperaturajor,exampleat plus 10". (3., with theforrnratt'ionof solutions having concentrations sufiiciently: high; for:the production of shaped structures; 1

Other!- objects. of. the-present invention will become apparent. fromthe following description.

Thetechnical-advance of the presentinvention is markedby thefollowingfacts:

(-1) The present invention produces-for the first timecellulose-etherswhich, ascompared with the alkalii-solublee celluloseethers, known hitherto, exhibit unusually valuable properties. I

Qnthemnehand;by their abilityto dissolvein-caustic alkali solution--at=v room temperature which; can be dissolved-in caustic alkali solutiononly by; cooling their suspensions or incompletesolutionsinrtcausticaalka lizsolrutiontoa low tem.

perature, particularly toa -.tem-perature at which freezing-on forming.of crystals occurs.

Qmthe othen and, they outshine the hitherto know I cellulose ethers:which will dissolve in caustic alkali solution at; room temperature orat as temperature n otg suhsta-ntially lower than room temperature-byadegreeof'viscosity of their solutions ,heretoforer never observed; insolutions. of any known cellulose ether which dissolves in.caustic,allsalrsolutionat room temperature, by" the far; better;filterabi'li-ty, 'spinnability and stability of their solutions and,Whatis still more important,yby theiinfinitelysuperior properties of theshaped structuresproducedtherefrom.

Owing; 130 21311656 properties they take precedence of-zall'alkali-solublecellulose ether known hither-to.

- (2.) Thexpresent invention produces for the first time cellulose;ethers which, although they directly; dissolve; in caustic alkalisolution at room temperature or at a: temperature not substantiallylowerthanroom temperature, to give solutions having a viscosity equalto, or not far remotefrom, the;viscosityrofsolu-tions of those celluloseethers from which-they. are: prepared and which can be stantially-ilower than room. temperature to yield solutions whichaare moreconcentrated than the solutions ofrthese cellulose ethers from whichthey areapirepared and whioh-canabe dissolved only with theaidiofitherefrigeration or freezing process.

( 49. The resentinvention produces for thefirst time cellulose etherswhich contain not more than one alcohol radical or hydroxy-acid residueper 2 or 3 or 4 C6H1o05-molecular units of cellulose and even celluloseethers which contain not more than one alcohol radical or hydroxy-acidresidue per more than 4 or even more than or 06111005- molecular unitsof cellulose and which, notwithstanding their low content in introducedalcohol radicals or hydroxy-acid residues, will readily and completelydissolve in caustic alkali solution at room temperature or at atemperature not substantially lower than room temperature with theformation of solutions which are suflicien-tly concentrated and viscousto be suitable for the production of shaped structures and which, owingto the fact that their cellulose residue is not or not substantiallydegraded and that their solutions have a considerable degree ofviscosity, yield shaped structures of supreme quality.

(5) The present invention produces for the first time cellulose etherswhich, although containing not more than one introduced alcohol radicalor hydroxy-acid residue per 2 or 3 or 4 or more Csl-lmOs-molecular unitsof cellulose. will as readily and completely dissolve in caustic alkalisolution at room temperature or at a temperature not substantially lowerthan room temperature as the hitherto known cellulose ethers containingmore than one alcohol radical or hydroXy-acid residue per 2CsI-ImOs-molecular units of cellulose, which will dissolve in causticalkali solution at room temperature. The products of the present casegive much more viscous solutions than the latter cellulose ethers, andtheir solutions ield shaped structures having properties infinitelysuperior to the properties of shaped structures obtainable from thelatter cellulose ethers.

(6) The present invention produces for the firs-t time cellulose etherswhich can be dissolved in very dilute cautic alkali solution, such ascaustic alkali solution of 4 or 5 or 6 per cent. strength at roomtemperature or at a temperature not substantiall lower than roomtemperature, although they contain not more than one alcohol radical orhydroxy-acid residue introduced ether-fashion into the cellulosemolecule per 2 or 3 or 4 or more ceHioOs-molecular units of cellulose,although their cellulose component is not degraded or not substantiallydegraded and although they are capable of being worked up into shapedstructures having dynamometric and other properties equal or notsubstantially inferior to the dynamome'tric properties of shapedstructures obtained from such cellulose ethers as will not dissolve orwill only partly dissolve at room temperature even in caustic alkalisolution of higher strengths and which can be dissolved therein only bythe refrigeration or freezing method.

('7) The present invention produces for the first time cellulose ethersthe solutions of which, although prepared at room temperature or at atemperature not substantially lower than room temperature, filter muchbetter and quicker than the solutions of the cellulose ethers from whichthey are prepared, even when their viscosity is equal to, or not farbelow, the viscosity of the solutions of the cellulose ethers from whichthey were produced and which can be dissolved only with the aid of therefrigeration or freezing method.

(8) The present invention produces for the first time alkali-solublecellulose ethers which can be dissolved in caustic alkali solution atroom temperature or a temperature not substantially lower than roomtemperature with the formation of solutions having a concentrationsuitable for the production of shaped structures.

(9) The present invention produces for the first time cellulose ethersthe solutions of which, with regard to their stability and spinnabilitysurpass the solutions of those cellulose ethers from which they areprepared and which can only be dissolved with the aid of therefrigeration or freezing process.

(10) The present invention offers for the first time the possibility ofproducing cellulose ethers which contain almost catalytic proportions ofa1- cohol radicals or hydroxy-acid residues linked ether-fashion to thecellulose molecule and which, nevertheless, will dissolve in causticalkali solution at room temperature or at a temperature notsubstantially lower than room temperature with the formation ofsolutions concentrated enough to be suitable for the manufacture ofshaped structures.

And more than that: It is possible to prepare according to the presentinvention cellulose ethers which will dissolve in caustic alkalisolution at room temperature or at a temperature not substantially lowerthan room temperature with the formation of solutions which have aconcentration suiiicient for the production of shaped structures, fromsuch cellulose ethers as are prepared, by acting upon alkali cellulosewith one mol. of an alkylating agent per about 20 or 30 or 50 Cal-11005-molecular units of cellulose, or with one mol. of a hydroxy-alkylatingagent per about 13 or per 27 or even per about 40 to 50C'sHmOs-molecular units of cellulose or by acting with one mol of amono-halogen fatty acid, upon similar amounts of cellulose.

Since, in the etherifying operation, not the whole amount of theetherifying agent added to the alkali cellulose is used up for thesubstitution of hydroxyl hydrogen atoms of the cellulose molecule, thenumber of alcohol radicals which are contained in the cellulose ethersis in general. considerably smaller than the number of alcohol radicalscomputed on the basis of the proportions of the etheriiying agents used.

Consequently, not only the proportions of ether ifying agents used forthe preparation of these cellulose ethers can be regarded as almostcatalytic, but also, and with still more justification, the ratios ofintroduced alcohol radicals contained in the final ethers themselves.

Apart from being a technical advance, the pos sibility of producingcellulose ethers which contain so incredibly low ratios of introducedalcohol radicals to 06211005 and which will dissolve in caustic alkalisolution at room temperature or at a temperature not substantially lowerthan room temperature, is a surprising feature of the present invention.

(11) The present invention produces for the first time cellulose etherswhich, although they will dissolve in caustic alkali solution at roomtemperature or at a temperature not substantially lower than roomtemperature, can be worked up into shaped structures excelling byunusually valuable properties, particularly by exceptional strength,extensibility, flexibility, elasticity and brilliance, excellent dyeingproperties and attractive appearance. In point of fact, with regard totheir properties, the shaped structures produced from the celluloseethers prepared according to the present invention are not in the leastinferior, and are in many cases even superior to the shaped structuresproduced from those cellulose ethers airman fromwhich they are producedandiwhich combo; only dissolved with-the aidiotthe refrigeratiomorfreezing method.

( 12) Thepresentinventionoffers the possibility Ofl3.-'-Cll1'60li- (whenWater isiused as precipitant) or.

an -indirect-' (when an alkali carbonateor carbon dioxideis used asprecipitant) recovery. of the.

caustic soda contained in' the solution Oil the initiaicelluloseetherand (whenan alkali'carboe' nate is used as precipitant) also of theprecipitating-agent in-theform of arr-alkali carbonate or, by wayoi'causticisation, in the form of the corresponding alkali hydroxide.

When confronted withthafollowing facts, the.

chemical and technical results-and" effects of the present invention arehighlysurprisins;

(1)- Heretofore, solutions of alkali-soluble cel fabrics, or sizingofyarnorthe like. Never were solutions of alkali-soluble cellulose ethersprepared by the refrigeration or freezing method precipitated 'with'theobject of-preparing specially valuable parent materialsfor-themanufacture of shaped structures. 1

Hence, the cognition that is possible to prepare from cellulose etherswhich will not dissolve or will only incompletely'dissolve in causticalkali solution at room temperature; cellulose ethers which'wi-lldissolve therein at roomtemperat'ure or at-a temperature notsubstantially lower than room temperature and-which, nevertheless, yieldshaped structures which quality is notonly novel but also surprising.

(2) It has been further established and is therefore generally assumedin the art:

(a) That shaped-structures coagulated out of solutions of alkali-solublecellulose ethers producedby'the refrigeration or freezing method areusually characterized by a decrease'in solubility in causticalkalisolution upon transitionfrom the solutiontothe solid state.

(b) That they do not so readily dissolve, in

caustic soda-solutionas do those'cellulose others will dissolve incaustic alkali solution at room temperature-or at a temperature notsubstantially low-er than room temperature, i.e. which contain more thanone introduced alcohol radical or hydroXy-acid radical per 2 or moreCeHmOs-nolecular units of cellulose, and

(c) Thattherefore cellulose ethers gelledfrom cellulose-ether solutionsprepared by the refrigoration or-freezing method will not dissolve incaustic alkali solution, except by freezing or an equivalent dispersionprocess;

And even the present inventor, who had been incessantly working atalkali-soluble cellulose others and at their conversion into shapedstructures since 1921 (see- British Specifiication No. 177,810) and who,for the first'tilme contrived and disclosed the refrigeration orfreezing methodf or dissolving such alkali-soluble celluloseethers aswill not-dissolve therein at room temperature or at a temperature notsubstantially lower than room temperature in 1923 (see BritishSpecification No. 212,854, for example page 3, lines 62 to- '71-)hitherto assumed that gels orprecipitates obtained by the precipitationof shaped'or shapeless solutions prepared 'byrefrigerating (particularlybyfreezing) suspensions or incomplete solutions incaustic-alkalisolution ofsuc-h" cellulose others as do not dissolveor onlyincompletely dis-- acid radical per 2: or. 3: or 4 ormorenGeHioQs-imolecular units of cellulose, mustnbe-incapableoi; dissolving (orincapable'of wholly. dissolving). in: caustic alkali solution at'roomtemperature: or' at-g a temperaturenot' substantially zlowersthan: room;

temperature.

Thisassumption was welr'founded" since, ace. cording; to What was knownaboutithe.propertiesa= of precipitates producedby neutralisationoracideificationof solutions of alkali-esolubl'e: colloids lor-a evencrystalloids) it could have been; believed} that the properties,particularly the ability-of-a-= cellulose ether precipitatedbyneutra-lisationxof its solution in caustic alkali solution to againdissolve in caustic alkalisolution willbe identical with the propertiesorthe cellulose ether before dissolution and precipitation.

In the light of these facts; it'becomes manifest:v that the presentinvention rests on a-perfectly novel and surprising discovery namelythe: dis-...

coverythat: those alk ali soluble cellulose others;

which. contain less than one, alcohol radical or" hydroxy-acid residueintroduced'into the cellu= lose molecule per one CsH1oO5.-molecular unitof cellulose, particularly, however, not more than one introducedialcohol radical. or. hydroxy-acidi residue per'2' or 3' or 4i or more.CGHIOOLi-mOIeQ-u; ular units ofcelluloseand which will .notdissolva orwill only incompletely dissolve in caustic-alkali solution at roomtemperature, or at atemperae ture not'substantially lower than roomtemperae ture can be converted into cellulose ethersawhich will readilyand completely or'at least practically; completely dissolve in causticalkalisolution at room temperature. or at? a: temperature-not! sub;-vstantially. lower than rooir'r temperature; by pre-:-. cipitating theircomplete or practically. complete. solutions: obtained: with theaid? ofthe refrigerae tion'method;

All the more is they present invention surpris-l ing, since itusesforjtheprecipitation; .coagulants: which have'never (prior to theiIIVGIIl'IlODS'OfIhlSEj inventor) been used'for the bulk precipitation:of: solutions of'alkali soluble cellulose ethersobany; kind, celluloseothers which will dissolvein causticalkali solutions at'roomtemperature-included;, with a view to the production of cellulose othersto be used as initial materials for the manufacture ofshaped structuresor otherusefularticles therefrom.

(3') Heretofore, only filtered solutions preparedi at roomtemperatureof. alkali-soluble cellulose: others which will not completelydissolve-in caus-. tic alkali solution at room temperature were;pre-.cipitated, with the purpose of OliSSOIVlIIElJhBPIB! cipitates and usingthe solutions thus obtained which, inmany cases were. present: in. thesaid;

ethers in large amounts, for example in proportions of 40 and even 90per cent. of the part which would not directly dissolve to 60 to percent. of the part which would dissolve.

Consequently, that method is merely a method for purifying the celluloseethers in question.

Now, since the cellulose ethers present in the filtered solutionsprepared at room temperature of these cellulose ethers will dissolve incaustic alkali solution at room temperature, the object of applying theaforementioned method to those cellulose ethers is neither to renderthem capable of dissolving in caustic alkali solution at roomtemperature, nor to prepare cellulose ethers having particularlyfavourable properties, i. e. the capability of yielding shapedstructures of highgrade qualities.

On the contrary: It is well known in the art that, owing to the very lowconcentration of the solutions so precipitated (in this method celluloseether solutions containing only 0.8 to 1.6 per cent. of cellulose etherare used) the cellulose molecule contained in the cellulose etherunder-. goes degradation; so much so, that the so purified ethers yieldin general shaped structures having more or less inferior propertiesinferior even to the properties of shaped structures prepared from suchcellulose ethers as in their original condition will completely dissolvein caustic alkali solution at room temperature.

But this difference in quality is nothing in comparison with thedifference between the shaped structures produced from cellulose etherspurified by the aforementioned method on the one hand and the shapedstructures made from cellulose ethers prepared according to the presentinvention on the other, the properties of the latter being infinitelysuperior to the properties of the former.

Now, the present invention shows that the reason for this tremendousdifierence is that, whereas in the purifying method discussed above theconstituents which do not dissolve at room temperature are removed fromthe ethers by filtering their solutions before precipitation, in thepresent process, these most valuable parts of the ethers are present inthe solutions in the dissolved state and then precipitated in animproved condition together with that part, if any, which from theoutset was capable of dissolving in caustic alkali solution at atemperature higher than the temperature used for the dissolution of theinitial cellulose ether.

It is therefore obvious that, face to face with all what is known in theart about the precipitation of solutions of alkali soluble celluloseethers, the present invention as such and its technical effects are mostsurprising.

In addition, the present invention is difierent from the methodcommented upon above by the precipitant used. For, whilst in the methodcommented upon above an acid or another substance capable ofneutralising the caustic alkali contained in the cellulose ethersolution is used as precipitant, the precipitants characteristic of thepresent invention are water or one or more alkali carbonates or carbondioxide or carbonic acid respectively, which do not neutralize causticsoda.

As stated above, the present invention comprises:

(1) Dissolving in caustic alkali solution at a temperature capable ofyielding a complete or practically complete solution of the desiredstrength,

A cellulose ether which will not dissolve or will only in part dissolvein caustic alkali solution at room temperature or at a temperature notsubstantially lower than room temperature and which yields solutionssufliciently concentrated to be suitable for the preparation of shapedstructures and other useful articles only if it is dissolved by coolingits suspension or incomplete solution in caustic alkali solution down toa temperature at which freezing or formation of crystals occurs, or

A cellulose ether which will not dissolve or will only in part dissolvein caustic alkali solution at room temperature or at a temperature notsubstantially lower than room temperature and which yields solutionssufficiently concentrated to be suitable for the production of shapedstructures and other useful articles only if it is dissolved at atemperature substantially lower than room temperature, and

(2) Precipitating the thus obtained solution with a precipitantselection from the group consisting of water, alkali carbonates, carbondioxide or carbonic acid respectively.

To realize the intent and purpose inherent in the present invention, theprecipitate thus obtained is, optionally after having been washed orwashed and dried, dissolved in caustic alkali solution preferably at ornear room temperature, and the solution thus obtained used for thepreparation of a shaped structure or any other useful article, bycoagulation.

In most cases, such cellulose ethers as will not wholly dissolve incaustic alkali solution at room temperature or at a temperature notsubstantially lower than room temperature, i. e. the initial materialsof the present process, contain less than one alcohol radical (which maybe a hydroxy-acid residue) introduced into the cellulose molecule perabout one CeH1oO5-molecule of cellulose, and preferably not more thanone introduced alcohol radical per about 2 csHmos-molecular units ofcellulose.

From the previous research-work it is further known that thosealkali-soluble cellulose ethers which contain not more than one alcoholradical linked ether-fashion with the cellulose molecule per about 3 or4 or 5 CeHmOs-molecular units of cellulose 01' even per about 6 to 15CeHmos-molecular units of cellulose, yield especially valuable shapedstructures (shaped structures having preeminent properties).

lhis fact can be seen from many examples of U. S. patents numbered1,683,831, 2,265,914, 2,265,915, 2,327,911 and 2,327,912 and BritishPatent No. 177,810 in which proportions of one mol. of alkylating-agentare used per about 2 to 15.5 CaI-ImOs-molecular units of cellulose forthe preparation of alkali-soluble alkyl ethers of cellulose, or fromPatent Nos, 1,722,927 and 1,857,097 in which proportions of one mol. ofhydroxyalkylating agent is used per about 2 to 7 CaHmOs-molecular unitsof cellulose for the preparation of alkali-souble hydroXy-alkyl ethersof cellulose, or from Patent No. 1,682,292 in which proportions of aboutone mol. of monohalogen fatty acid is used perabout 1.2 to 5.5Col-11005- molecular units of cellulose for the preparation ofhydroxy-acid ethers of cellulose.

. Consequently, the present invention can also be defined as follows:

The present invention comprises:

(1) Dissolving in caustic alkali solution a cellulose ether whichcontains less than one alcohol radical (which may be a hydroxy-acidaim-7 T residue) in-troduceu into the cellulose molecule: per about oneCsHicQwmolecular.units of eel-- lulo'se, and preferably not more thanonei-ntroi duced: alcohol radical. or hydroxyeacid: residue per 2- 013Lor 4 or 5 or-"l ll or '15 or :30 or more GI-IioO5-mol-ecular units.oiscellulos-e, at a. temperature which yieldsthe-mostcomplete-..solution obtainable with the relativecelluloseether, and J(2)Precipitating the :thus obtained solution with a precipitant selectedfrom the. group consi'stingof water, alkali carbonates, carbon dioxideand carbon ic acid respectively. 1

Needless to-saypalso this definition of the invention impliesthe-dissolving: in caustic alkali solutionof the optional-1y washed-orwashed-and. dried precipitate: in caustic alkali "solution and. usingthe so Obtai-ned soldtionofi the said precipitate for the manuf acturepfshaped structures or other useful articles. Although; at bottom, thecarrying, out of the present process practice is comparatively simple,the-working conditions may 'bevariied within wide limits, withoutdepartingfrom. the spirit: ofthe-invention. ltzisxthereforenot-intendedto limit the inventionztothe following description andto.:the examplesillustrating the practicaLexecution .01 the process; for:exampleto .the particularsflgiven therein .as' to the types of theinitial. ialkal-iesoluble celluloseethers (i; .e.. as to the nature .ofzthe :alcoholradical or. alcoholradicals introduced ether-fashion intothecellulose molecule and as to. the; representatives set forth by way of.examples 1.101? thevarious types ofithe various initiallcelluloselethersand as .to'the processes and methods for't-he productionof theinitial-cellulose vothers). asto. the. concentration of the solutionsof. the initial cellulose. ethersrrto he precipitated, as. tothetemperature .or temp eratures. at which .the. solutions are; pre pare.d,-v aszto the-.amount-onamounts of precipitan-ts used, ,asto the.-detailsof. the. treatment according to the present process, as to theprocesses or methods and temperatureslof the preparation ofthesolutions-of the cellulose others. preparedaccording to the present'in'v'entionand .as ,to the quantitative composition. of thesesolutions/asto the substances which optionall ymay be addedT'to thesesolutions, as tothe method-s offworking up these solutions intosl'iapedi'structures or other useful articl eSLa's to'themethodsof'converting the ce'l'-' lulose-ethers prepared according to thepresent invention into their xanthates, as to-the methods for.worliingup the cellulose ether xanthatesprepared according: to" thepresent invention into shaped structures, as to-the after=treatnient ofthe" shaped structures or other useful articles accordingto the-presentinvention,- etc. etc.

it -is-to be understood that'in the present invention cellulose'ethers--maybeused'as initial materials which are made by any processormethod whatever allowing *ofthe production of cellulose ethers of theaforementioned types; For. instance; if the working conditionsare'suitablefor the preparation ofsuch cellulose ethers as have thesolubility relationships -set forth above; any one of the processes andyor methods described in Patent 'Nos. 1,589,606, 1;683}831-, 1,683;682,1,722, 927,=1,682,292, 1,682,294, 2,095,524, 2,327,911, 2,327,912,22655919, 2,265,918 and 2,306,451 and British Specification -No.462;45610r in U. S. applications Ser. No. 715254; .now -aloan doned,Ser. No. :9=1;.7.90 no.w,.abandonedzior' any other :process or'method'.which may the used for the.r..prenaration- .of cellulose ethers :ofzithe:aforementioned: types, may heiusedzforzthe production.

of I the: cellulose others used: as initial mate-rials imthe presentinvention;

In. other words: Not only-suchalhali soluble cellulose ethers' oftheaforementioned-typesas can 'beprepared-bythe processes andimethodsdescribed-in the specificationsset forth in-theforegoing paragraph, .butalso such al'kali-sol-ublelcellulose ethers of the aforementioned typesmay be used as initial materials in the present in.- vention can beprepared by any other processor method suitablefor the preparatiQm ofcellulose ethers of ftheaforemention'ed types.

It is further to be understood that, in the pres-- ent-inven-tion eithersimple or mixed alkali-soluble cellulose others can be employed. -Asmixed ether-s the following may lee-named: by way of example: ,7

. Cellulose .ethers containing; in their molecule two different alkylgi1oups,,cell-ulose ethers contai-ning in their molecule an-alkyl groupand ,a

hydroxyalkyl group; .cell-ulose etherscontainingin their. molecule. twodifferent hydroxyl-alkylz groups, cellulose others containing iii-theirmolecule an alkyl group and 3a hydroxy-alkyl group, cellulose ethers-.contai-ningin their'molecu-le two different hy-droxy-acid residues,cellulose ethers:

containing in their molecule an alkyl-group and a 'hydroxy-acid residue,cellulose ethers' contain.- ing in their molecule a v a hydroxy-acidresidueand soon.

These mixed ethers can be obtained, for example, by treating underconditions adapted for. the preparation of such-cellulose others ashave.

the solubility relationships set forth-above-simultaneously or in eitherorder with two different alkylating agents, or with-an alkyla ting agentand arhydroxy-alkylating agent, or with two different.hyj'drox-walkylating. agents, or with two different halogen fattyacids, or with an.a1k}ylating agent and a halogen fatty .acid, .,or witha hydroxy-alkylating agent and a halogen fatty. acid, etc, etc, Incaseofsimultaneous treatment,

the twodifferent reagents may. be added" to the. alkali cellulosetogether, for. example mixed, or.

one after the other in either order.

The. carrying: out of the present invention in.

practicenomprises the followingsteps:

(1) .D-issolving incaustic alkali solution atv a temperature capable ofyielding a complete. or practically complete solution of the desiredstrength, r

A cellulose :ether which will not whol-ly-dissolye. in caustic alkalisolution at room temperature .or.

Acellulose ether which'will rnot whollyrdissohze;

inrcaustic alkali solution :at. room temperature. or at: a temperaturenot; substantially lowerzthan room "temp erature and iwhic'hayieldssolutions sutficiently concentratedito be suitablefor theiiproduction'of shapedstructures'. and otherwuseful articles only if: it .is:-.dissolved .a temperature.

substantially lower. than room. temperature;

(2) Precipitating the thus obtained solution' with a precipitantselected from thegroup consisting. of; water, :railka'li carbonates,carbon dioxide :or carbonic acid-respectively,

(3) Dissolving in caustic alkali solutiomtthe. cellulose.ether preparedby. the .processiconsisthydroxy-alkyl' group. and

13 ing of the steps set forth above under (1) and (2), and

(4) Working up the solutions of the final cellulose ether into a shapedstructure or any other useful article.

Concerning (1) Since, to obtain the full effect or effects of thepresent invention, it is important to start from solutions containingthe whole or practically whole substance of the initial cellulose etherin the dissolved state, it is advisable to conduct the dissolution ofthe initial cellulose ether at a temperature at which a complete oralmost complete solution of the desired con centration of the celluloseether in hand is produced.

In most cases, the upper limit of this temperature varies with theproportion of the cellulose ether desired in the solution.

For example: Some representatives of the cellulose ethers of theaforementioned types will dissolve with the formation of complete oralmost complete solutions of any strength only when their suspensions orincomplete solutions in caustic alkali solution are cooled to atemperature at which freezing or formation of crystals occurs.

Other cellulose ethers of the abovementioned types will dissolve withthe formation of complete or almost complete solutions containing, aconsiderable proportion (for example Ste 9 per cent.) of cellulose etheronly by freezing, but will dissolve with the formation of complete oralmost complete solutions containing a moderate proportion, for example4 to 5 per cent. of cellulose ether by cooling their suspensions orincomplete solutions in caustic alkali solution to a temperature atwhich no freezing or formation of crystals occurs, for example to minus2 or to C. or to a temperature between 0 C. and plus C., and willdissolve with the formation of complete solutions or almost completesolutions containing a small proportion, for example 2 per cent. ofcellulose ether at room temperature.

Other cellulose ethers of the aforementioned types will dissolve withthe formation of complete or almost complete solutions containing aconsiderable proportion, for example 6 to 9 per cent. of cellulose etherwhen their suspensions or incomplete solutions in caustic alkalisolution are cooled to a temperature at which no freezing or formationof crystals occurs, for example to minus 4 or minus 2 C. or 0 C., andwill yield moderately concentrated solutions, for example solutionscontaining 4 to 5 per cent. of cellulose ether at somewhat highertemperatures, for example at a temperature between 0 C. and plus 5 C.and Will dissolve with the formation of complete solutions or almostcomplete solutions containing a small proportion, for example 2 percent. of cellulose ether at room temperature.

As a matter of course, the temperatures set forth above are mentioned byway of example and it is to be understood that they are to be regardedas the upper limits of those temperatures which are necessary to obtaincomplete or almost complete solutions of the cellulose ethers inquestion.

In other words: Complete or almost complete solutions will also beobtained when lower temperatures as set forth above are used in thedissolving step.

The upper limit of the temperature at which the dissolving step is to beconducted further 14'. depends on the strength of the caustic alkalisolution used.

In this respect it must be understood that withcaustic alkali solutionsof lower concentrations recourse must be taken to freezing also in suchcases in which a moderate proportion, and at any rate to lowertemperatures than the temperatures mentioned above also in such cases inwhich a small proportion of the cellulose ether is desired to be presentin the solutions intended for precipitation according to the presentprocess. p r V The cellulose ethers used as initial materials in thepresent invention may be dissolved either in the form of the crudeproducts resultant from the etherifying operation or they may be firstisolated therefrom, for example by washing the crude reaction massesresulting from the etherifying step, which washing may or may not bepreceded or followed by acidification. If the acidification follows theWashing operation, it is recommendable to free the washed and acidifiedethers from acid by washing them again after the acidification.

The initial cellulose ethers may be in the wet or moist or in the drystate, prior to mixing with the caustic alkali solution.

Concerning (2): The temperature of the precipitants may be varied.within wide limits. Thus, for instance, they may be kept at roomtemperature or at a temperature below room temperature or above roomtemperature or at a raised temperature. In many cases, the precipitationoccurs quicker and more complete and the amount of theprecipitantsneoessary for thorough precipitation is smaller when theprecipitants are used at a raised temperature.

If water is used as precipitant, it is employed in the form of pure, i.e. distilled water or in the form of any water of ordinary purityoccurring in nature. If desired or expedient, in both cases, smallproportions of organic or inorganic substances may be added to the waterto be used as precipitating agent.

The alkali carbonates may be used in the solid state or in the form oftheir solutions. In the latter case, the solutions may be either dilutesolutions or solutions of moderate strength or concentrated or saturatedor supersaturated solutions.

'If desired or expedient, other alkaline and also neutral salts may beadded to the alkali carbonate solutions.

The carbon dioxide may be used in any available form, i. e. in the formof carbon dioxide produced by any process or method known in thetechnology of carbon dioxide or in the form in which it occurs in natureor in the form of those by-products or waste-products which containcarbon dioxide, for example in the form of flue gas or lime kiln gas orin the form in which it is evolved in some fermentation processes. Itmay be used in the undiluted state or diluted with other gases, or inthe form of a medium containing carbon dioxide. It may be further usedin the form of a dispersion or solution in water.

It is advisable to conduct the precipitation with stirring or otherwiseagitating and in cases in which small quantities by volume of the liquidprecipitants or in which precipitants in the solid form are used, evenwith energetic kneading in a kneading machine whose blades may or maynot be dentated.

' The; precipitated-masses canzbe' :further worked: immediately or soonafter their precipitatidniris'e completed or; before ;-being ,worked, 1they imam-fibeheated or warmed; or remain-ion a;shorter or longertime(for'instance'l hour toafi hoursaor= longer) at room temperature.

Before being dlSSO1VECL'thG precipitated cell-ue lose ethers may bewashed or washed and'there-l after dried. In many cases, however,particularly, when water is used as precipitant; they maybe dissolved inthe unwashed'state. lniith'ilatller case, they should be separated fromthel'moth'ero liquor by straining, filtering, centrifuging:- orathelike.

Concerning (3): The dissolution in caustioal-l kali solution ofthe-ethers prepared according :to; the I present invention by theprecipitation of the solutions of the:initial-cellulose vethers-;car-1:-,be--v carried out by anymethod known in -the art. Since theoelluloserethers prepared-accordinggto=- the .present invention willdissolve ,in caustic-alkali solution at room temperature.oreatia temeperature not substantially lower than room temperature with theformation of comple'teor practically complete solutionshavingconcentnations suitable for the production of shaped-structures,the dissolving may be conducted inmost cases. at, or only slightly belowroom temperature.

If so desired, for some reason or another, thedissolution-may beconducted at atemperature" below room temperature or even below 0 C.

Concerning (4) The working up-of the'cellulose ether prepared accordingto the present in vention into shaped structures,forexample arti' ficialthreads, film, coatings of' any kind and the like, is eife'cted, forexample; by' bri-nginga' solution of a cellulose ether prepared inaccordance with the invention, into the de'sired'shape and acting uponthe thus shaped solutibn With a coagulating agent, for example one:oftheco-'- agulating baths oknown;in.the" art' of' making shapedstructures from :alkalil-solubl'ei .2 cellulose; ethers and/or viscose.

The cellulose ethers preparedgaccordingqto:thei present invention may beworkediupyzinto:shapeclit structures also insuch a mannerythat theirshaped solutions are contacted with an -agent or agents which has or.have acoagulating effect.- on the shaped solution and aplasticizingefiect; on the freshly coagulateol material. Aszxagentse,which exert a coagulating and plasticiZi-ng,aotion, baths containing atleast. 25 per cent. strength of sulphuric acid monohydrate (for.exeample 25 to about '70 per cent. of sulphuric acid, monohydrate), orsuch proportion of another strong mineral acid as will produce aneffectin. the manufacture of shaped structures similarvto that givenbysulphuric acid containing ,at least 25 per, cent. of P125904, haveproved suitable.v The coagulating and plasticizing of theqsolution mayalso occur in two step-sby acting upon the shapedz; solution first withone or more-agents, which hav j.: a, coagulating but no-oronly.littleplasticizirig: eifect on the shaped solutionsandthenzwithone-* or mor agents (for example strong mineral acids, particularlystrong sulphuric acid)*"whioh'have'- a plasticizing eiTect on thefreshly coagulated" material.

As far as supportless'shaped structures, such as artificial threads,artificial hair, artificial. straw, film, bands, strips or the likeareconcerned, the shaping and coagulating may be effected by extrudingthe cellulose ethersolution through suitably formed openings into a coagulating bath-.211. Supportless; shaped; structured? face on which it isat least partly immersed-find the:- coagulatingubath :and; 1 thereafter:Jremovin'g the; coagulated shaped: structure from: the; saido surfaceandfinishing :the shaped structure-in ;the'

usual gmanner. In-case of: such, shaped SlLITLlC-i' Ttures aslarecombined with; arigid .or. pliable sup;

port,,-suc'h :.as coatings, layers: and impregnations; O a ly kind,.-' dessin s; :of:- abrics; textilemprint ing, -.book+cloth ;I.tracing+;cloth, sizing-t: Ofu yarn;

paper-sizing, paper-like, surfacing etc'rthe zshape ping and coagulatingmay be accomplishedgby;

wholly or partially. coatin l-rimpregnatinggprinting on j otherwise;coveri-ng,;-or 5 imbuingz cellulose ether solution gavrigidjlorv'plia,,:sup;-:: port and, iwith; or without; intermediate: drying,

treating- /the material,with a3 coagulating-y bat-h byweither:introducing;the;;materialinto v:thettJfJ 'th (the agulating: bath or by;spraying=--,the :coa ul-atin r.;,

bath on the materialor conductingrthe;imaterial. through a mistof, thecoagulating;,ba-th;,;or;by-,; 1; any other method of-iapplyingaliquidq-paste {to f a rigid or pliable support. ln-rPatentiNos.1,722,928;- ,1,682,293;.2,327,$l11,

2,327,912,, 2,265,917; 2,306,451,: and 2,265,9-18;1 2,231,927,-2,265,916-,and;2,2 24,874 and-,U-.S.:appli.--

cations ,--Ser. Nos. 71,254 nowyabandonedmandt,

91,790 nowabandoned, British Specification-i No.1; 462,456 and British:Specification -No. 28.808136; processesflorv methodsof working, up;so1utions-,,of 3 alkali-soluble. cellulose ethersinto shaped-istruce,

tures l are Y described and illustrated-by; examples so thoroughly that,instead- ;of repeatinggl-thew working (formulae; it sufilces :to referto ithesaid specifications which, will serve asiuseiul vdescrip-i tionof examplesfor the-conversion, of the alkali-,1

otheriuseful qarticlesa Itlmust be .pointedeout,expressly that theyworking up of the cellulose ethers prepared acesolublecellulosee-ethers-,-prepared :according {toe the. r present invention 5-into, shaped'i structures by. coagulating a shaped solution-.containing; gal

least one cellulose ether. produced-accordingjto the. present inventionby ,a v-medium-acontaining at least; one alkaltcarbonate ,or, accordingto', the; process/described innU, S. Patent .-2,231,92 -7 ing whichwater is-used las: coagulant,- for shapedsolutions of alkali-soluble.cellulose ethersscohol, particularlya. halohydrin, such as a,di-pchlorohydrin, in short, insofaras,it is @compati ible with thealkali-soluble cellulose ethers', anyy structures according :to-,thepresent invention. I

Useful. parent materials 11501 the production-of;

Any suitablesoftening agent, suchaszglycerine orjaoglylcol brasugar,such ast-glucoseor a soap. or, Turkey-red .oil, or a drying tornon-drying'oil,2 orahalogenderivative ofadiorpolyeva-lent alt-g.

,chloroh'ydrin or a monochlorohydrim oraethylene' 'lose ethers prior to.their-conversion-fintoshaped:

shapedjstructures are obtained-whenthe cellulose ethers preparedaccording to the presentziinven-i tion are xanthated, for exampleaccordingritol the processes described ,in =1 Patent Nosz; 2,02,1;861*,.:.-.

1, 53,097,- 1 ,91o,44o and-2,265,914.;

The xanthates of the cellulose ethers-prepared.:;- J according tothe-present,invention.;can;;be producedby a ting-Jon -the scelluloseetherswith icam bon bisulphide in presence of alkali. The carbonbisulphide may be caused to act either upon the cellulose ethers in thesolid form in presence of caustic alkali solution, for example upon amoist alkali compound of a cellulose ether or upon a mixture of acellulose ether with caustic alkali solution or upon a suspension of acellulose ether in caustic alkali solution or upon a solution of acellulose ether in caustic alkali solution.

The methods of producing Xanthates of cellulose ethers and the workingup of such Xanthates into shaped structures are in the four aforesaidspecifications as well as in U. S. Patents 2,265,917, 2,265,918 and2,306,451 and British specifications 459,122 and 462,456, described andillustrated by examples in so exhaustive a manner that it is sufficientto refer to the respective parts of the said specifications which willserve as useful descriptions of, and examples for, the conversion intotheir Xanthates of the alkali-soluble cellulose ethers preparedaccording to the present invention and the working up of the thusobtained xanthates into shaped structures.

It must be pointed out expressly that the work" up of the xanthates ofthe cellulose ethers prepared according to the present invention intoshaped structures or other useful articles may also be effectedaccording to the processes described in British Patents 472,888 and472,933 namely by the use of alkali monocarbonate or bicarbonatesolutions as coagulating baths.

Any suitable softening agents, such as glycerine or a glycol or a sugar,such as glucose or a soap or Turkey-red oil, or a drying or non-dryingoil, or a halogen derivative of a dior polyvalent alcohol, particularlya halohydrin, such as a dichlorohydrin or 9, monochlorohydri'n'or'ethylene chlorohydrin may be added to the solutions of the xanthatesof the cellulose ethers produced according to the present invention.

With regard to the practical carrying out of the present invention inpractice, it is impossible to indicate every condition for success inevery particular case and it is to be understood that preliminaryexperiments cannot be avoided to find what the conditions necessary forsuccess when using a particular kind of cellulose, a particular initialcellulose ether, a particular method for the production of the initialcellulose ether and so on.

In order to explain the nature of the present invention, the followingspecific examples are set forth. It is to be understood that theinvention is not limited to these examples, to the precise proportionsof ingredients, the times and temperature and sequence of steps setforth; the parts are by weight:

Example 1 A to N A. 1000 parts of air-dry wood-pulp of a quality andviscosity customary in the viscose art or cot ton linters of similarquality are steeped in 10,000 to 20,000 parts of caustic soda solutionof 18 per cent. strength at 15 C. and the mixture allowed to stand at C.for 1 to 24 hours. The resulting mass is then pressed at to 18 C. to3000 to 3500 parts and comminuted at 10 C. for 1 to 3 hours in aWerner-Pileiderer shredder or another suitable comminuting machine or ina Werner-Pfieiderer xanthating machine whose blades may be dentated,after which the shredded alkali cellulose is allowed to mature for 72hours at 10 C. Thereupon 200 parts of ethylene chlorohydrin or 110 partsof ethylene oxide are added 18 in one or several portions and thereaction mass is shredded for about 3 hours at 10 C. 1

The crude reaction mass is, without being washed or otherwise treated,mixed with such quantity of a caustic soda solution of approximatestrength as to yield a solution or suspension containing about 6 percent. of the cellulose ether in 8 to 9 per cent. of caustic sodasolution and kept at room temperature with continuous or intermittentstirring for 1 hour. Thereafter the thus obtained mixture is cooled downwith stirring to minus 10 C. and kept at this temperature with stirringfor 20 minutes. After that time the frozen mass is allowed to come backto room temperature.

The solution thus obtained is a viscose solution which to the eye isperfectly free from undissolved constituents or fibres.

Although, in such circumstances, filtration is unnecessary, to secureperfect freedom from dust or any other impurities which might during orafter the reaction have accidentally gotten into the reaction mixture orsolution, the solution is filtered by way of precaution throughmedicated cotton Wool. It filters only at a pressure of 8 to 10atmospheres and also this rather slowly and with repeated change of thecotton wool.

The viscosity of the filtered solution is about 18 to 20 as comparedwith glycerine of 1.26 specific gravity.

A film of 0.02 mm. thickness produced from this solution by coagulationwith a solution containing in 1000 parts by volume 160 parts of H2804and 320 parts of Na2SO4 has a dry tenacity of about 20,500 lbs. persquare inch and a wet te nacity of about 4500 lbs. per square inch. Thefiltered solution is with continuous stirring precipitated with eighttimes its weight of water of to C. and then kept at 75 to 80 C. for 15minutes.

The precipitate thus obtained is separated from the mother liquor on astraining cloth or in a filter press or in a centrifuge and then washedwith not water and thereafter wtih cold water until free from alkali,and pressed.

The washed and pressed cellulose ether can be dissolved either in themoist state or after having been dried, if desired, after dehydrationwith alcohol and, if desired, after exhaustion with ether.

If the moist cellulose etheris to be dissolved without drying it isnecessary to determine its water content, for example by drying aweighed portion at C. to constant weight.

For dissolving the moist cellulose ether it is intimately mixed at 15 to18 C. with so much caustic soda solution of appropriate strength astoyield a mixture containing 7 per cent. or the hydroxy-ethyl celluloseand 93 per cent. of caustic soda solution of 8 to 9 per cent. strength.

If it is desired to dry the ether before its dissolution, to obtain asolution of same concentration, the dry ether is mixed direct with an 8to 9 per cent. caustic soda solution at 15 to 18 C. in a proportion of 7parts of the dry ether to 93 parts of caustic soda solution.

In both cases, the dissolving which is conducted with continuousstirring proceeds smoothly and results in a solution which is free orpractically free from undissolved constituents.

It is then filtered. It filters excellently well at a pressure of 2 to 3atmospheres and has a viscosity of about 38.8 as compared with glycerineof 1.26 specific gravity. lution, the final cellulose ether has aviscosity (In a 6 per cent. s0;-

' assist 19. of about 19 to 20'as compared with glycerine of 1.26specific gravity.) Q r Afte being fr d from. gas bubbles. in the usualmanner-,thev filtered solution is, according to the.

methods. set forth a vawork d up. into shaped stru tur sr u a ar ificialthreads. for example artificial silk or staple fibre, artificial hair,artificial straw, film of every kind, bands and plates of every kind,plastic masses of any description, adhesives and cements, finishescoatingsand layers of every kind, particularly such as are applicable infinishing, filling and dressingof textile fabrics, sizing of yarn, orused; as thickening agent or fixing agent for a pigment in textileprinting and the like, or as paper-like surfacing or paper-sizing, or inthe, manufacture of artificial leather or of book-cloth orof tracingcloth or of transparent paper or oftransparent cloth and the like. i

A film of 0.02 mm. thickness produced from this solution at roomtemperature has a dry te-.- nacity of about 21,800 lbs. per square inchand a wet tenacity of about 5700 lbs. per square inch. NorE. Theoriginal ether, dissolved under refrigeration thus gives a film showing.a drytenacity. of 20,500 lbs. per sq. inch, and a wet tenacity of 4500lbs. per sq. inch. The treated ether gives a similar film showing a drytenacity of .8 lb perq. inch. and aw t tena ty f 5700 lbs. per sq. inch.It is notattempted to explain the reason for this tremendous. increasein. wet tenacity. i From this example it can be seen, That, whereas, toproduce a solution of. 6 per cent. strength, the initial cellulose ethermust be dissolved by the freezing. method... the cellulose etherprepared therefrom-according. to the present example forms easily, asolution. of; 7

per cent. strength on being dissolved at room temperature and,

That. nevert eles (q) The viscosity of the .solutionof the. celluse thpr pared ac ord ng othe pr sent example is equal to theviscosity of asolution of the initial cellulose ether of same strength,

(b) A 7 per cent. solution of the cellulose ether prepared according tothe present examplefilters more easily than a 6. per cent. solution ofthe initial cellulose ether of same strength, and

(c) The shaped structures produced from the the cellulose ether preparedaccording to the present example have at least as excellent, prop:erties as the shaped structures prepared from the solutionof the initialcellulose. ether.

B. The process is conducted as in A. but with thedifierence that thequantity of water used for the precipitation is only twotimes the.weight of the'solution of the initial cellulose ether. 1

With regard to its solubility, with regard to the viscosity andfilterability' of its. solution. and with regard to the shapedstructures. produced therefrom, the cellulose ether prepared accord ingto B is similar to the cellulose ether prepared according to A. 1

C. The pr cess is conducted as. in A. but with the exception that,before being dissolved and, precipitated, the initial Cellulose etheris, isolated from. the crude reaction product, by the fol-low ingmethod:

The crude reaction mass as such or after having been neutralised oracidified (for example, withv sulphuric. acid of to. 10 per cent.strength),

is washed with water and then, pressed and, after v the water content ofthe pressed product has.

beendetermined, mix-ed. direct with so much] caustic soda solution ofappropriate'strength as to yield a mixture'containing about 'l'percent.of the cellulose ether and 93 percent. ofa caustic soda solution of 8 to9 per cent; strength and then frozen, thawed, filtered and worked up asdescribed in A. The 7 per cent. solution of the isolated initialcellulose ether prepared by the freezing method has a viscosity of about38 as compared with glycerine of 1.26 specific gravity and filtersslowly at a pressure of 8 to 10 atmospheres, whereas the '7 percent.solution prepared at room temperature from the final cellulose ether,has a viscosity of about 32 as compared with glycerine of 1.26v specificgravity and filters very well at a pressure of 3 to 4 atmospheres.

A film of 0.02 mm. thickness produced from the 7 per cent. solution ofthe initial cellulose ether has. a dry tenacity of about 19,000 lbs. persquare inch and a Wet tenacity or about 6,000 lbs. per square inch, anda film of same thickness produced in the same manner from the 7 percent. solution of the final cellulose ether has a dry tenacity of about20,000 lbs. per square inch and a wet tenacity of about 6,600 lbs.square inch.

Consequently, notwithstanding that it dissolves perfectly in causticsoda solution at room temperature, the cellulose ether preparedaccording to C is, with regard to its properties and the properties ofthe, shaped structures produced therefrom, equal or similar to theinitial cellulose ether which can be dissolved to a 7 per cent. solutiononly by the freezing method.

D. The process is conducted as in C}, but with the difierence that thequantity of water used for the precipitation is only two times theweight of the solution of the initial cellulose ether.

With regard to dissolving it in NaOH solution, with regard to. theviscosity and filterability of its solution and with regard to theproperties of,

the shaped structures produced therefrom, the cellulose ether preparedaccording to this example is similar to the cellulose ether preparedaccording to D.

E. The process is conducted as in any one of A to D, but with thedifference that the cellulose ether precipitated from the solution ofthe initial cellulose ether is not washed, but only freed from themother liquor by straining and/or pressing.

After the water and caustic soda contained in the cellulose etherseparated from the mother liquor has been determined, the ether, isdissolved at room temperature in so much caustic soda solution ofappropriate strength as, together with the water andcaustic sodaadhering to the ether, to yield a 7 per cent. solution of the celluloseether in caustic soda solution of 8 to 9 per cent. strength. I

With regard to dissolving it in NaOH solution at room temperature, tothe properties of-its solution and to the properties of the shapedstructures produced therefrom, the cellulose ether prepared according toE is similar to the cellulose ethers prepared in A to D.

F. Mode of procedure as in A to C, but with the difference that, insteadof hot water, cold water (for instance at 12 to20 C.) is" used as.

precipitating. agent, the quantity of the. water being 20 times theweight of the solution of the initial cellulose ether.

G. The. process is conducted as in any one. of A toD, but with theexception that, instead of the hot water used therein, a sodiumcarbonate solution of 28 per cent. strength at 50 to 90. C. is used asprecipitant.

With regard to dissolving it in NaOI-I solution at room temperature, tothe properties of its solution and to the properties of the shapedstructures produced therefrom, the cellulose ether prepared according toG is similar to the cellulose ethers prepared in A to D.

H. The process is conducted as in any one of A to D, but with theexception that, instead of the hot water used therein, a sodiumcarbonate solution of 20 per cent. strength at 20 C. is used asprecipitating agent.

With regard to dissolving, to the properties of its solution and to theproperties of the shaped structures produced therefrom, the celluloseether prepared according to H is similar to the cellulose ethersprepared in A to D.

The sodium carbonate solution .of 20 per cent. strength may be used alsoat a higher temperature,'for example at 50 or 70 C. or at a still highertemperature with equal or similar effect.

J. The process is conducted as in any one of A to H, but with theexception that the solution of the initial cellulose ether is a solutionof 5 per cent. of the cellulose ether in 8 to 9 per cent. caustic sodasolution and has been prepared at Although the solution of the initialcellulose ether is practically free from undissolved constituents, itfilters slowly at a pressure of 8 to atmospheres, whereas an equallycomplete solution of '7 per cent. strength of the final cellulose etherprepared at room temperature filters very easily at a pressure of 2 to 3atmospheres, the viscosity of the solution of the initial ether beingabout 6 and the viscosity of the solution of the 7% solution of thefinal ether being about 32 as compared with glycerine of 1.26 specificgravity. (On account of its low strength, the solution of the initialcellulose ether is not comparable with the solution of the finalcellulose ether with regard to viscosity.)

A film of 0.02 mm. thickness produced from the 7 per cent. solution ofthe final cellulose ether that has been prepared at room temperature hasa dry tenacity of about 26,000 lbs. per square inch and a wet tenacityof about 6,600 lbs. per square inch.

K. The process is conducted as in any one of A to H, but with thevariation that the solution of the initial cellulose ether is a 4 percent. solution of the cellulose ether in 8 to 9 per cent. caustic sodasolution and has been prepared at plus With regard to its dissolving, tothe properties of its solution and to the properties of the shapedstructures produced therefrom, the cellulose ether prepared according toK is similar to the cellulose ethers prepared in A to D.

L. The process is conducted as in any one of A to H, but with thedifference that the solution of the initial cellulose ether is a 2 percent. solution of the cellulose ether in 3 to 9 per cent. caustic sodasolution and has been prepared at C.

With regard to its solubility and to the properties of its solution, thecellulose ether prepared according to L is similar to the celluloseethers prepared in A to D.

A film of 0.02 mm. thickness produced from a 7 per cent. solution of thefinal cellulose ether in 8 to 9 per cent. caustic soda solution preparedat room temperature has a dry tenacity of about 23,000 lbs. per squareinch and a wettenacity of about 5,800 lbs. per square inch.

M. The process is conducted as in any one of.

A to L but with the difierence that, instead of water or sodiumcarbonate solution, the solution of the initial cellulose ether isprecipitated with carbon dioxide which is introduced in the gaseous forminto the solution.

After a short time thickening of the solution occurs, after which theether precipitates in a gelatinous form.

The introduction of the carbon dioxide with stirring is continued forabout 1 hour during which time the mother liquor starts separating.

Thereafter the mass is placed on a straining cloth and washed withWater.

The washed precipitate is then pressed and, after its water content hasbeen determined, dissolved (in this case, without washing) at roomtemperature in such a quantity of a caustic soda solution of appropriatestrength as to yield a 7 per cent. solution of the final cellulose etherin caustic soda solution of 8 to 9 per cent. strength.

A complete solution free or practically free from undissolvedconstituents results, which filters very easily at a pres-sure of 2 to 3atmospheres. The viscosity of the 7% solution of the final celluloseether is about 31 as compared with glycerine of 1.26 specific gravity.

A film of 0.02 mm. thickness produced from this solution has a drytenacity of about 20,000 lbs. per square inch and a wet tenacity ofabout 6,000 lbs. per square inch.

Before being precipitated with carbon dioxide, the solution of theinitial cellulose ether may be diluted with Water, for instance with to200 per cent. of water calculated on the weight of the solution.

N. The process is conducted as in any one of A to M, but with thedifference that the washed precipitate is stirred with 2 to 3 times itsWeight of hydrochloric acid of 4 to 5 per cent. strength, allowed tostand therewith at room temperature for 3 hours, then collected on astraining cloth or in a filter pres-s or in a centrifuge and then washedwith water until free from acid.

Before being dissolved, the washed precipitate may be dried, if desired,after dehydration with alcohol, and, if desired, with subsequentexhaustion with ether.

The washed precipitate is in the moist or dry state dissolved in causticalkali solution at room temperature to form a '7 per cent. solution ofthe cellulose ether in caustic soda solution of 8 to 9 per cent.strength.

With regard to dissolving, to the properties of their solutions and tothe properties of the shaped structures produced therefrom, thecellulose ethers prepared according to N are similar to the celluloseethers prepared in A to D.

Instead of in a 8 to 9 per cent. caustic soda solution, the celluloseethers prepared according to any one of A to N may be dissolved at roomtemperature or at a lower temperature in more dilute caustic sodasolution, for example in caustic soda solution of 5 or 6 or 7 per cent.strength.

Examples II A to N The process is conducted as in any one of theExamples I A to N, but with the difference that the shredding andmaturing of the alkali cellulose and the treatment of the alkalicellulose with the ethylene chlorohydrin or ethylene oxide are conductedat 1 C. (instead of 10 C.).

v Examples III A to N Theprocess is conducted as in any one of the 23Examples I A to N,'but with the difference that the shredding andmaturing of the alkali cellulose and the treatment of the alkalicellulose with the ethylene chlorohydrin or ethylene oxide are conductedat 18 0.

Examples IV A te -N The process is conducted as in any one of theExamples I A to N, but with the difierence that the shredding andmaturing of the alkali cellulose and the treatment ofthe"alkali"cel'lu'lose' with the ethylene chlorohydrin or ethylene oxideare conducted at 21 C.

As a matter of course, in proportion to the higher temperatures ofshreddin maturing and treating the alkali cellulose with the h'ydroxyethylating agent, the viscosities of the solutions of the initial andfinal cellulose ethers of "Examples II A to N to IV A to N are lowerthan the viscosities of the solutions of equal strength'preparedaccording to the Examples I A toN.

Notwithstanding this fact, the viscosities of the final cellulose ethersolutions are equal or not considerably lower than the visco-sities ofthe initial solutions, the filtering capacities of the former being ingeneral superior to the filtering capacities of the latter. Theproperties of the shaped structures produced from the solutions of thefinal cellulose ethers are equal to, or not substantially differentfrom, the properties of the shaped structures made from the solutions ofthe initial cellulose ethers.

Examples V A to N The process is conducted as in any one of the ExamplesI A to N, but with the exception that, instead of 200 parts ofethylenechlorohydrin or 110 parts of ethylene oxide, 100 parts ofethylene chlorohydrin or 55 parts of ethylene oxide are used for theetherification of the alkali cellulose (i. e. only half as much of theetherifying agent) and that, instead of being dissolved to a 7 per cent.solution in caustic soda solution of 8 to 9 per cent. strength, theinitial and the final cellulose ether are dissolved to a 6 per cent.solution of 8 to 9 per cent. strength, the solution of the initialcellulose ether being prepared with the aid of the freezing operation asdescribed in Example I A and the solution of the final cellulose etherbeing prepared at 15 to 18 C(as described in same example.

The former solution is, before filtration, complete and thus practicallyfree from undissolved constituents and the latter solution is equallycomplete and perfectly free from undissolved constituents. The solutionof the initial cellulose ether filters Very slowly at a pressure ofabout atmospheres, whereas the solution of the final cellulose ethersfilters very well at a pressure of about 3 to 4 atmospheres.

The dynamometric properties of the shaped structures produced from theshaped solutions of the final cellulose ethers are in many casessuperior to the dynamometric properties of the shaped structuresproduced from the shaped solution of the initial celluloseether. Thus,for instance, a film of 0.02 mm. thickness prepared from a 6 per cent.solution of the final cellulose ether in 8 to 9 per cent. caustic sodasolution has a dry tenacity of about 22,600 lbs. per square inch and awet tenacity of about 5200 lbs. per square inch, whereas a film of samethickness produced from a solution of same concentration of the initialcellulose ether has a drytenac'ity of about 18,000

24 .i lbs. per s'qu'ar'einch and a wet'tenaclty of about 4000 lbs. persquare inch. 7

Examples VI A to N The process is conducted as in anyone of the ExamplesV A tell, but with the variation that, instead of at 10 (3.,the'shredding and the maturing of the alkali cellulose and the reactionbetween the alkali cellulose and the ethylene chloroh'ydrin or ethyleneoxide are conducted at 21 C. v

Examples VII A to N v Mode of procedure. as in any one of the Examples IA to N, but with the exception that the initial cellulose ether isprepared'asfollows:

1000 parts of air-drywood-pulp of a quality and viscosity customary inthe viscose art or cotton lintersof similarqu'ality are-steeped in10,000 to 20,000 parts of. caustic soda solution or 18.5 per cent.strength at 15 C. and the mixture allowed to standatl15 C. for l to24hours. 7 The resulting mass isthen pressed to 3000*parts and'comminuted at 20 C. for 1 to 3 hours in a Werner Pfleiderer shredderoranother suitable comminuting' machine or in a Werner-Pfleidererxanthating machine whose blades may be dentated, whereupon parts ofethylene chlorohydrin' or 55 parts of ethylene oxide are added-in one orseveral portions. The reaction mass is shredded for about. 3 hoursat.20. C; and then allowed to stand at 15 to20 C; for 15 hours.

A further difference between thisexamp'le and Examples I A to Nisth'at', instead of being dissolved to a 7 per cent. solution incaustic soda solution: of 8 to 9 percentpstrength; the initial and thefinal cellulose'ethers are dissolved to 6 per cent. solutions'in causticsodasolution of 8 to 9 percent. strength. 7

Examples 'Vm A to N g The process is conducted as in'Examples VII A toN, but with the variation that, instead of-l00 parts of ethylenechlor'ohydrin or..55 parts of ethylene oxide, 70 parts of ethylenechlorohydrin or 35 parts of ethylene oxide are used in the etherifyingstep.

Although prepared at .15 to 18 C., the 6 per' cent. solution of thefinal cellulose ether in 8 to,

9 per cent. caustic soda solution filters easily at a pressureof 2atmospheres, whereas a v5 per cent. solution of the initial. cellulose.ether in caustic soda solution of!) per cent. strength cannot befiltered at all through cotton. wool but must be filtered through aloose cotton fabric;

Consequently, a3 per cent. solution of the initial cellulose ether incaustic soda solution of 9 prepared bytheifreezing method must be usedasthe initial-cellulose ether sold -v percent. strength tion.

Whereas, as stated above; the 5 per centlsolution of the initialcellulose ether was not*filterable, the 6 per cent. solution of thefinal cellulose ether prepared at room temperaturefiltersexcellently ata pressure of ,2 atmospheres.

The dynamometric properties of th shaped structures produced from thefinal cellulose ether aremore or less equal-tothe dynamometric'pr0p-,.erties of the shaped structures preparedgfrom';

the-initial cellulose the 5 per cent. solution of ether filtered throughcloth.

' Exdmples lX'A ZO'N Theproce'ss conducted as, Examples 1 A to N or VIIIA N, but with the'eXQepfiOI-I contacted Withthe hydroxythat, beforebeing ethylating agent, the alkali cellulose is matured for 24 or 48 or64 hours at 20 C.

Examples X A to N The process is conducted as in Examples VII A to N orVIII A to N or IX A to N, but with the difference that, after the secondshredding, the reaction mass is allowed to stand for 24 or 48 or 64hours at 15 to 20 C. instead of for 15 hours.

Examples XI A to N The process is conducted as in any one of theExamples I A to N to X A to N, but with the exception that, instead ofbeing pressed to 3000 to 3500 parts, the alkali cellulose is pressed to2000 to 2500 parts.

Examples XII A to N The process is conducted as in any one of theExamples I A to N, but with the difference that the initial celulloseether is prepared as follows:

1000 parts of air-dry wood-pulp of a quality and viscosity customary inthe viscose art or cotton linters of similar quality are steeped in10,000 to 20,000 parts of caustic soda solution of 18 per cent. strengthand the mixture allowed to stand at room temperature for 1 to 24 hours.The resulting mass is then pressed to 2000 to 2500 parts and comminutedat 20 C. for 1 hour in a Werner- Pfleiderer shredder or another suitablecomminuting machine or in a Werner-Pfleiderer xanthating machine whoseblades may or may not be dentated, whereafter the shredded alkalicellulose is allowed to mature for 72 hours at 20 C. Thereupon 37 to 38parts of ethylene chlorohydrin or 20 parts of ethylene oXide or 50 partsof glycerol alpha-monochlorohydrin or 26 to 30 parts of propylene oxideare added and the reaction mass is shredded for about 3 to 6 hours at 15to 20 C.

In this example the solution of the initial cellulose ether and thesolution of the final cellulose ether are 6 per cent. solutions incaustice soda solution of 8 to 9 percent. strength. The solution of theinitial cellulose ether prepared b the freezing method filtersexceedingly slowly and diflicultly, whereas the solution of the finalcellulose ether prepared at plus 10 to 18 C. filters easily at apressure of 4 atmospheres.

The dynamometric properties of the shaped structures prepared from thesolution of the final cellulose ether are not substantiall differentfrom the dynamometric properties of the shaped structures produced fromthe solution of the initial cellulose ether,

Examples XIII A to N Mode of procedure as in Examples XII A to N, butwith the difference that, instead of 37 to 38 parts of ethylenechlorohydrin or 20 parts of'ethylene oxide or 50 parts of glycerolalpha-monochlorohydrin or 13 to 15 parts of propylene oxide, parts ofethylene chlorohydrin or 10 parts of ethylene oxide or to parts ofglycerol alpha monochlorohydrin or 13 to 15 parts of propylene oxide areused in the etherifying step.

The properties of the initial cellulose ether and its solution and ofthe shaped structures produced therefrom are similar to the propertiesof the final cellulose ether and its solution and of the shapedstructures produced therefrom.

Examples XIV A to N The process is conducted as in Examples XII 26 that,instead of at 20 C., the alkali cellulose is matured at 25 C.

Examples XV A to N The process is conducted as in any one of theExamples XII A to N to XIV A to N, but with the variation that, insteadof to 2000 to 2500 parts, the alkali cellulose is pressed to 3000 to3400 parts.

Examples XVI A to N .The process is conducted. as in any one of theExamplesIAtoNor IIAtoNorIIIAtoNor IV A to N, but with the exceptionthat, instead of 200 parts of ethylene chlorohydrin or parts of ethyleneoxide, 200 to 300 parts of di-methyl sulphate ormonochloroacetic acid(in the form of a concentrated aqueous solution of sodiummonochloroacetate) or 150 to 280 parts of glycerolalpha-monochlorohydrin or 150 parts of propylene oxide are used in theetherifying step.

Examples XVII A to N The process is conducted as in any one of theExamples XVI A to N, but with the difierence that, instead of theproportions of etherifying agents used therein, 100 to 150 partsofdi-methyl sulphate or monochloroacetic acid (in the form of aconcentrated aqueous solution of sodium monochloroa-cetate) or 75 toparts of glycerol alpha-monochlorohydrin or 75 parts of propylene oxideare used in the etherifying step.

Examples XVIII A to N The process is conducted as in any one of theExamples XII A to N to XV A to N, but with the difference that, insteadof the ethylene chlorohydrin or ethylene oxide used therein, 50 parts ofdi-methyl sulphate are used in the etherifying step.

Examples XIX A to N The processis conducted as in any one of theExamples XVIII A to N, but with the difierence that, instead of50'parts, 30 to 40 parts of dimethyl sulphate are used in theetherifying step, the solution of the initial cellulose ether being a 3per cent. solution in caustic soda solution of 8 to 9 per cent.strength.

Examples XX A to N The process is conducted as in any one of theExamples I A to N to XIX A to N, but with the difierence that, insteadof the proportions of etherifying agents used therein, a mixture of 50parts of ethylene chlorohydrin or of 70 parts of glycerolalpha-monochlorohydrin or of 30 to 40 parts of ethylene oxide or of 70to 30 parts of propylene oxide and 100 parts of di-ethyl sulphate ordi-methyl sulphate or 100 parts of monochloroacetic acid (in the form ofsodium monochloroacetate), or a mixture of 50 to 100 parts of di-methylsulphate and 100 parts of di-ethyl sulphate or 100 parts ofmonochloroacetic acid (for example in the form of sodiummonochloroacetate), or a mixture of 50 to 100 parts of diethyl sulphateor of (ii-methyl sulphate and 100 parts of monochloroacetic acid forexample in the form of sodium monochloroacetate), is used in thepreparation of the initial cellulose ether.

Examples XXI A to N The process is conducted as in any one of theExamples XX A to N, but with the difference that, instead of theproportions of etherifying agents used therein, a mixture of 25 to 50parts of ethylene chlorohydrin or of 30 to 60 parts of glycerolvalphan'ionoc'hloroliydrin orbof to 30 parts of ethylene oxide and 50partsof di-ethyl sulphate or di-methyl sulphate or 50 parts ofmonochloroacetic acid (in the form of sodium monochloroacetate), or amixture of to50 parts of di-methyl sulphate and 50 parts of diethylsulphate or monochloroacetic acid (in the form of sodiummonochloroacetate) or a mixture of 25 to 50 parts of di-ethyl sulphateor di-methyl sulphate and 50 parts of monochloroacetic acid (in the formof sodium monoch-loroacetateyis used in the preparation of the initialcellulose ether. i

Examples XXII A to N v The process is conducted as in any one of thepreceding examples, but with the exception that the initial celluloseether is prepared as follows:

A quantity of any one of the alkali celluloses used for theetherification in any one of the foregoing examples corresponding to1000 parts of air-dry parent cellulose is placed in a rotating autoclaveor an autoclave provided with a stirring device, whereupon 200 to 500parts of precooled ethyl chloride are added and the material is heatedto 60 to 100C. and kept at this temperature for 6 to 12 hours.

Examples XXIII A to N Mode of procedure as in'Examples XXII Ato N, butwith the variation that the parent cellulose ether is prepared byhydroxy-alkylating any one of the ethyl celluloses prepared according toany one of the Examples XXII A to N.

'The NaOH content of the crude reaction mixture resulting from theethylating operationis determined by analysis, whereupon, optionallyafter compensating the amount of NaOH used up in the ethylating reactionby supplying to the reaction mixture the equivalent or a larger quantityof NaGH in the form of powder or of a strong solution, for instance ofto percent. strength, the reaction mixture is treated with 50 to 150partsof ethylene chlorohydrin or '70 to 210 parts of glycerolalpha-monochlorohydrin or with 25 to '75 parts of ethylene oxide or with32 to 100 parts of propylene oxide as described in any one of thepreceding relative examples for alkali cellulose.

-In those of the foregoin examples in which the alkali cellulose ismatured for a longer time than ,48 hours, the time of maturing may beshortened down, for example to 48 or 24 hours and in all foregoingexamples the maturing can be entirely dispensed with.

In the foregoing examples in which sodium carbonate solutions are usedfor the precipitation of the initial cellulose ether solutions, insteadof the sodium carbonate solution, a solution containing 12 per cent. ofsodium bicarbonate at 20 to 45 C. can be used.

In these examples; instead of the sodium carbonate or sodium bicarbonatesolution used for the precipitation of the initial cellulose ethersolution, also a stronger or weaker solution of an alkali carbonate or asolution containing an alkalicarbonate and an alkali bicarbonate or asolution containing an alkali carbonate and a neutral salt or a solutioncontaining an alkali carbonate and another salt having alkaline reactionor a solution containing an alkali carbonate and an organic substance ora solution containing a mixture of an alkali carbonate with two or moreof the substances set forth above in this'paragraph can be used asprecipitants In the foregoing examples the primary or secondary sodiumcarbonates used as precipitants may be wholly orpartially replaced byone or more alkali salts having alkaline reaction of other weakinorganic or organic acids, for example by sodium tetraborate (borax) orby dibasic or tribasic sodium phosphate or by an alkaline sodiumsilicate or by sodium acetate or by sodium sulphite or the like; c

When asolution of. one or more alkali carbonates is used for theprecipitation of the solution of the initial cellulose ether, the alkalicarbonate or carbonates contained in the mother liquor of theprecipitate may be either separated from the caustic alkali containedtherein by any known method andthe caustic alkali used in the process asdescribed above or the alkali carbonate or carbonates may beconvertedinto the corre sponding caustic alkali-by the well knowncausticizatlon method. Ineither case also the alkali carbonate or atleast part of it is re-utilized in the process in a circuitous course:in the former as alkali carbonate, i.e. as precipitant, in the latter ascaustic soda for the production of the initial cellulose ethers' and/orfor dissolving the initial and/.or'flnal cellulose ethers.

If desired, carbon dioxide may be introduced into themother liquor andinto the first washing waters in which case the caustic soda containedtherein is converted into sodium carbonate, the

result being that the mother liquor and at least the'first washingwaters can, after being reinforced by an additional quantity of thecarbonate or carbonates, be used in the precipitating step andthusreintroduced into the process in a cyclic course.

When carbon dioxide is used as precipitant, the mother "liquor and thewashing water contain alkali carbonate. They may therefore be treated asindicated above.

Instead of being prepared by steeping the cellue lose in excessof'caustic alkali solution and removing the excess by pressing, in anyone of the preceding examples the "alkali cellulose may be prepared bymixing the cellulose in a suitable mixing apparatus, .-for example ashredder or a kneading machine or a mill or a disintegrator or an edgerunner orthe like with the amount of caustic soda solution correspondingwith the quantity remaining in the alkali cellulose used in the relativeexamples after pressing (for examplewith 2000' to 2500 parts of causticsoda solution of 18 per cent. strength). The mixing of the cellulosewith the-caustic alkali solution may be conducted at room temperature orat a temperature above room temperature, for example at 24 to 30C., orwith cooling, for example, to 15 or 10 C., or lower. The time of mixingmay be varied within wide limits, for example from 1 hour to 24 hours orlonger.

As a guiding line with regard to the question whether or not the alkalicellulose should be allowed'to' mature before being brought togetherwith the etherifying agent or agents, may, among others, serve thedesired viscosity of the final solutioniof the products of theinvention, i.'e. of the solution which is to be worked up into shapedstructures, and in connection therewith the viscosity of the kind ofcellulose used as starting material for'making the initial celluloseether. If itis desired to give the solution a definite viscosity, thenthe alkali celluloseproduced from the kind of cellulose used issubjected to a maturing process, if Without maturing this kind ofcellulose yields a higher viscosity. If, however (in a preliminaryexperiment), the solution exhibits from the first the desired grade ofviscosity, that is without maturing, the maturing is superfluous. Now,as the viscosities of the different kinds of cellulose on the market(linters and wood-pulp) differ very much from one another, the questionof maturing depends in most cases on the one hand on the viscositydesired of the solution of the final ether intended for the manufactureof shaped structures, and on the other hand on the viscosity of the kindof cellulose used as starting material.

In the foregoing examples, any excess of any volatile etherifying agentswhich has not been used up in the etherifying reaction may be re coveredby condensation or distillation.

In the foregoing examples, instead of cellulose, a conversion product ofcellulose-for instance, a cellulose hydrate or a, hydro-celluloseproduced by chemical action on cellulose, such as mercerisation withsubsequent washing and, if desired, drying: or by treating with a stronginorganic or organic acid or a mixture of both; or by treating with adilute solution of a mineral acid; or by treatment with a zinc halide;or by a mechanical process, such as grinding in presence of water or thelike; or any oxy-cellulose-in short any body of the cellulose groupwhich has been proposed for the manufacture of viscose or of any othercellulose derivatives or compounds or of ammoniacal-copper-oxidecellulose can be used as start ing material for the production of theinitial cellulose ether.

Consequently, the term cellulose used in the description and claims is,wherever the context permits, intended to include cellulose, itsconversion and oxidation products, such as cellulose hydrate,hydrocellulose, acid-cellulose and the like, in short, any body of thecellulose group which has been proposed as starting material for thepreparation of cellulose derivatives or cellulose compounds of any kind.

If feasible or expedient, in the foregoing examples, instead of thechlorinated etherifying agents used therein, equivalent quantities ofthe corresponding brominated or iodinated reagents (for example alkylbromides or alkyl iodides or monobromohydrin or monoiodohydrin orethylene bromohydrin or ethylene iodohydrin or bromo-acetic acid oriodo-acetic acid etc.) may be used.

If feasible or expedient, in the foregoing examples, instead of thealkylating or hydroxyalkylating agents used therein, equivalentquantities of alkylating or hydroxy-alkylating agents containing otheralkyl or hydroxy-alkyl groups can be used, for instance methyl chlorideor propyl chloride or an amyl chloride or a butyl chloride or butylenechlorohydrin.

If feasible or expedient, instead of ethylene oxide or propylene oxide,other alkylene oxides, such as butylene oxide or glycide, in short allsuitable compounds which contain an ethylene oxide ring can be used inthe foregoing examples.

If feasible or expedient, instead of 'alkyl halides or di-alkylsulphates, equimolecular amounts of their substitution or additionderivatives, for ex ample halogen alkyl amines, such ashalogenalkyl-dialkyl amines or their hydro-chlorides can be employed inthe foregoing examples.

If feasible or expedient, in the foregoing relative examples, instead ofthe choloracetic acid, the equimolecular quantity of an ester ofchloroacetic acid, for example methyl or ethyl-chloroacetate or ahalogen derivative of a homologue of acetic acid, for instancealpha-chloropropionic acid or alpha-chloro-isobutyric acid oralpha-bromo-propionic acid or alpha-bromo-isobutyric acid or the like oran alkali salt or an ester thereof may be employed.

As stated above, the solutions of the cellulose ethers preparedaccording to the invention may be worked up into shaped structures orother useful articles by any process whatever known or proposed for themanufacture of shaped structures or other useful articles fromalkali-soluble cellulose derivatives, viscose included. for instance bythe processes described in U. S. Patents 1,722,928 or 2,327,358 or2,327,359 or 2.265.917 or 2306451 or 2,265,918 or 2,231,927 or, 2265916,or 2.224.874, or British Patents 459,122 or 462,256, or Britishapplication No. 28,808 36.

The directions given in these specifications for the production ofshaped structures from alkalisoluble cellulose ethers in general andfrom alkali-soluble hydroxy-alkyl derivatives of cellulose in particularare so thorough and detailed and, in addition, illustrated by so manyexamples that, instead of repeating the descriptions and statements inquestion, the inventor preferred to confine himself to a reference tothe said specifications.

As stated above, the cellulose ethers prepared according to the presentinvention can be converted into their xanthates according to theprocesses described in U. S. Patents 1.858.097, 1,910,440, 2,021,861,2,265,914, 2,265,917, 2,265,918 and 2,306,451 and in British Patents459,122, 459,124, 462,283 and 462,456, and the thus obtained xanthatescan be worked up into valuable shaped structures and other usefularticles.

In this respect special attention is called by way of example to theseven methods described in Patent No. 1,858,097, to the nine methodsdescribed in British specification No. 462,456 and to the nine methodsgiven in the inventors U. S. Patent 2,296,856 and to the examplescontained in these specifications.

Since the practice of the process of making xanthates of celluloseethers and of working them up into shaped structures is exactly as setforth in the specifications set out in the foregoing two paragraphs andexplained therein by numerous examples, it appears superfluous to repeathere all particulars relating to the conversion of the cellulose ethersprepared according to the invention into their xanthates and to theworking up of these xanthates into shaped structures and other usefularticles under various working conditions and to give here examplesdemonstrating all possible modifications of working the presentinvention.

With regard to the processes or methods for the conversion of thexanthates of the cellulose derivatives prepared according to theinvention, special attention is called by way of example to theprocesses of British Patents 472,888 and 472,933 which, when applied tothe xanthates of the present cellulose ethers, yield excellent shapedstructures, at the same time economizing their production.

If desired, the extensibility of the shaped structures such as threadsor film or coatings or the like produced according to the presentinvention fromthe cellulose ethers or from their xanthates may beincreased by treating them either in the course of their manufacture,for example after coagulation and washing or in the finished wet or drystate with suitable shrinking agents, for example, with some of theshrinking agents mentioned in Patents Nos. 1,898,098,

2,001,621; 1,989,101 1,989,100, 2,004,875 and 2,004,876. 1 i i Whereverthe context permits, the term alkali cellulose means alkalicellulose-prepared in the usual manner, namely by steeping cellulose incaustic alkali solution and removing the excess of the latterbypressing, or by mixing cellulose with such an amount of 'caustic alka-lisolution as is desired to be present in the final alkali cellulose.

The expression etherification used the specification and claims coversalkylati'on or ,ara-I- kylation. or hydroxy-alkylation or production ofhydroiqpacid derivatives, ether covers simple alkyl or ara-lkyl andhydroxyealk-yl ,orjhydroxyacid others and also mixed others, forexamplethe mixed others hereinbcfore named.

The term hydroxy-alkyl is intendedto include the halogenated ornon-halogenated radicals of dior polyvalent alcohols in conjunction withone or more oxyg-enscr hydroxyls.

Wherever the context permits, the terms alkyl, alkylate, alkylatingagent, alkylation are intended to include unsubstituted or substituted.(forexample aralkyl groups) alkyl groups, alkylate with alkylatingagents thatcontain unsubstituted or substituted (for examplearalkylgroups) alk-yl groups, alkylating agents that contain unsubstituted orsubstituted (for example aral-kyl groups) alkyl groups, alkylation withalkylat-i-ng agents that contain unsubstituted or substituted (-forexample aralkyl groups) alkyl r up The term hydroxy-alkylating agents isintended to include halogen'derivatives" of di or polyhydric alcohols,particularly halohydrins, such as monohalohydrins and alkyleneioxides.

In the specification and claims :theexpression halogen fatty acid? ormonohalogen fatty acid includes, wherever the context permits,monoch-lor., monobromand mcnoiodo fatty acids themselves, theirderivatives (such as esters) and their salts, as Well as substances andmixtures of substances which yield monohalogen ,f-atty acids or theirderivatives. I

The term a cellulose ether is intended to includea single ether or amixture of two or more ethers (of the kinds defined herein) and it alsoincludes simple or mixed others (of fined herein) The term (alkalicarbonate used in the description and claims is, wherever thevcontextpermits, intended to include the primary and secondary alkalicarbonates,

The expression shaped structures used in the specification and claims isintended to include: Artificial threads, particularly artificial silkand staple, fibre, artificial hair, artificial straw, .film of everykind, bands and plates of every kind, plastic masses of any description;adhesives and cements, finishes, coatings and layers of every kind,particularly such as are applicable in fine ishing, filling and dressingof textile fabrics, sizing of yarn, thickening agents or fixing agentsthe kinds dofor pigments in textile printing anclthe like; pa-

per-like surfacing, paper-sizing; in the manufacture of artificialleather or of book cloth or of tracing cloth or of transparent paper orof tran parent cloth and the like.

The term artificial threads denotes artificial threads and spun goods ofall kinds, for instance artificial silk, artificial cotton, artificialwool, artificial hair and artificial straw of any kind.

The present application is a division of application Ser. No. 217,776filed July 6, l938, now abandoned which corresponds to a. Britishapconcentrated to be suitable for being; shaped and coagulated toproduce'regenerated shaped'structures, which processcomprisesdissolvingisuch other by maintaining a mixture containingsuchether inaqueous caustic alkali solution "togethe'rat a temperature nearthe freezing'point until-said other has substantially completelydissolved-and precipitating the desired product from'tthe sold-- tion soproduced by mixing together under agitation a bulk of said solutionand aprecipl'tan-tfnr the dissolved ether, which'precipitant-iscapable ofleaving a solution ca able of-neutralizing strong mineral acids, andwhich precipitant is selected from the group consisting-of alkalicarbonate, alkali bicarbonate, carbon dioxide; carbonicacid andmixtures-thereof, and continuing suchagita tion and mixing until saidether is-preclpitatedsout of such solution, separating said precipitatedother from the mother liquor and thereafter rc dissolving same in anaqueous caustic alkalisolution at a temperature substantially higher'than the temperature at which said first dissolving step wasaccomplished, and in such red-issolvingst-ep,

using such proportions of the materials as to yield a solution ofsuchcellulose ether of a sufiicien't concentration therein to be suitablefor the'directproduction therefrom of shaped regenerated arti-= ficialstructures by coagulation, the aqueous caus-' tic alkali solution usedin such second mentioned dissolving step being one "which would not-atthe temperature used insaid seconddissolving step, dissolve the initialcellulose ether. 7,

2.,A process for producing a solution suitable for the preparation ofshaped structures, which process comprisesrefrigerating amixture-containingan undissolved cellulose'ether, which etherwill' notdissolve substantially completely in caustic alkali solution atatemperature not substantially lower than room temperature, in causticalkali solution until a formation of ice crystals occurs and until thesaid ether dissolves, and thereafter agitating a bulk of the-solutionthus obtained and during such agitation incorporatingthere-e with. aprecipitant consistin essentially of at least one sub-stance selectedfrom the group consisting of alkali carbonate, alkali bicarbonate,carbon d1- oxide, carbonic acid and mixtures thereof, :to pro duce aprecipitate, and finallydissolving this-pre-- cipitate in caustic alkalisolution at atemlieraturc much nearer to room temp crature' than thatused in said first mentioned dissolving-step toform'a solution of thedesired cellulose other concentration, the said last mentioned causticalkali solution being itself incapable of dissolving the initialcellulose ether at the temperature used "in said second dissolving step.Y

3. A process as claimed in claim 1, wherein the said precipitation stepis conducted at a tern pera-ture not substantially below room temperature.

4. A process of transforming a cellulose eth'er which will not readilydissolve substantially com pletely in aqueous caustic alkali solution atsome given temperature not substantially lower than room temperature toproduce .a solution sufficiently concentrated in such cellulose ether tobe suit-able for being shaped and coagulated to produce regeneratedshaped structures, which process comprises refrigerating a mixturecontaining such ether in aqueous caustic alkali solution to atemperature near ice temperature until said ether has substantiallycompletely dissolved therein and afterwards precipitating the desiredproduct from the solution so produced by mixing and agitating saidsolution in bulk with a precipitant for the dissolved ether whichprecipitant is itself incapable of neutralizing the alkali, and whichprecipitant is selected from the group consisting of alkali carbonate,alkali bicarbonate, carbon dioxide and carbonic acid and mixturethereof, to precipitate such dissolved ether, and thereafter dissolvingthe precipitated cellulose ether in an aqueous caustic alkali solutionat a temperature much higher than the temperature at which the firstmentioned dis- 34 solving operation was eflected and the caustic alkalisolution used in said second dissolving step being incapable ofdissolving the initial cellulose ether at the temperature at which saidsecond dissolving step is carried out.

ANTONIE LILIENFELD, Administratria: c. t. a. of the Estate of LeonLilienfeld, Deceased.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 798,027 Ernst Aug. 22, 19051,599,508 Altwegg et al Sept. 14, 1926 1,814,208 Dorr et al July 14,1931 2,157,530 Ellsworth et a1. May 9, 1939 2,190,445 Ellsworth et al.Feb. 13, 1940 2,249,754 Ellsworth et a1 July 22, 1941 2,296,857Lilienfeld Sept, 29, 1942

